Abstract

The status of the alien American freshwater crayfish Procambarus clarkii Girard and of the native African freshwater crab Potamonautes loveni in the lower to middle reaches of the Rivers Gilgil, Malewa and Karati flowing into Lake Naivasha were assessed by trapping between 1999 and 2003. P.clarkii was common in the lower reaches of the Rivers Gilgil and Malewa having colonised these rivers by upstream movement from Lake Naivasha. P.loveni was only recorded at sites on the River Malewa where P. clarkii was absent. These sites were upstream of a weir which P. clarkii may not as yet have been able to cross. It is hypothesized that P. loveni may have inhabited the lower stretches of these rivers prior to colonisation by P. clarkii but has since been predated or out-competed by the aggressive P. clarkii. It is also possible that P. clarkii has effectively wiped out downstream stocks of P. loveni by acting as a vector for a crustacean disease such as crayfish plague, Aphanomyces astaci. Alternatively, P. loveni may be absent from the lower reaches of rivers flowing into Lake Naivasha because physicochemical conditions are unsuitable for it, for example, the water temperature may be too high for it in the lower reaches of these rivers. P. clarkii is now common in water bodies across Kenya including rivers flowing into Lake Victoria; it may cause ecological damage in such waters.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: